31 i"&: _. -. ... ' "J" . ,? : "'.- ( ( 7:""' . friends), and entertainlnent func- tions (he has played a game with it, in which the computer tested his ability to add two-digit nun1bers, and he can make the teletype keys act like organ keys and produce musical tones), but what really interests him is a fourth category of functions-one he calls "baby-sitting the house and its occu- pants." Just then, Mrs. Prugh, who had been out visiting a friend, drove up in her car and obligingly demon- strated Category 4. \Vhen she opened the garage door, which Mr. Prugh had connected to the computer by sensors, PDP 8-L printed out a terse bulletin: "GDO" garage door open). Several minutes later, it issued another brief statemen t: "GDC" (garage door closed) "If the garage door had stayed open for more than five minutes, the com- puter would have instructed it to close," Mr. Prugh said. "My goal ]S to rnake the computer the silent sentinel around the house. I have it in mind to connect it to the windows, the furnace, and the basen1ent floor. It will be able to give off alarm signals if the windows are opened unexpectedly, or the fur- nace overheats, or the basement floods. I'm lin1ited by the an10unt of spdre J::.'.. . . . , " A" ') 'þ" 'i:: :':: ' :': , 1f)ft];! .- \ y, .. . " ' '., : t ' 7:lïr :. ;; ....0. t":1 ' . . tÏ1ne I have to work out each progran1 and by the computer's capacity, which is only four thousand words. A simple message like '\Vake up' uses thirty to forty words. Another limitation is n10ney. Let's say the computer finds a window open and rings SOlne bells hut no one is at home to hear them You'd want ]t to be able to telephone tht.: po- lice automatically. But ['ve decided, for now, not to get involved in the finan- cial and legal transactions I'd have to have with the phone company before I'd be allowed to connect the computer to the phone and have it place calls Of answer the phone when [ was away and dialled it to get a status report on the house." Mr. Prugh is quick to adlnlt that a number of relatively inexpensive gadg- ets-a clock, a calculator, a player piano, a text-editing typewriter, d bur- glar-alarm system, and so on-can, separately, perforn1 many of the tasks his computer has learned, and also that his con1puter is "not what we at the Defense Departn1ent call cost-effec- tive." However, he admires the con1- puter's versatility ("No clock can cope with my income taxes"), and he he- lieves that a home con1putel will be econon1ically feasible in the not very ........,. fi(1Zu- )) d]stant future "In the two years since I purchased my con1puter, the price for a slightly more capacious model has dropped to sixty-five hundred dollars," Mr. Prugh told us. " [he trend in the con1putel b llsiness is for prices to con- tinue to fall. 1\1y guess is that by ] 975 you'l1 he c:lhle to get a hOlne computer for two thousdnd dollars. And it would be sin1pler if, instead of trying to add a cOlnputer to an already built house, you sat down with an architect and pl lnned how you'd build in the sensors in a new hOllse. The home con1puter could be progralnmed to plan menus, to keep track of the children's dentist appointments, and to keep a running grocery list. ()nce the grocery list was con1piled, the computer could tell you the "horte t possible route through the aisles of your supermarket to n1dke your purchases. Computers are alread} mon- itoring patients in hospitals. \Vhat the home computer will do someday will simply depend on the ingenuJty of the person who is dealing with it." . S IGN observed on the door of the Renaissance Art Gallery, an upper East Side establishment: "No B rows- jng This \V eek."